Greg Bernstein gregb@grotto-networking Grotto Networking Young Lee ylee@huawei

1. A Framework for the Control and Measurement of Wavelength Switched Optical Networks (WSON) with Impairments draft-bernstein-ccamp-wson-impairments-01.txt Greg Bernstein gregb@grotto-networking.com Grotto Networking Young Lee ylee@huawei.com Huawei Dan Li danli@huawei.com Huawei 73rd IETF – Minneapolis, MN, November 2008

2. Contributors • Ming Chen (Huawei) • Rebecca Han (Huawei) 73rd IETF – Minneapolis, MN, November 2008

3. A Framework for WSONs with Impairments • What are impairments and how do they relate to routing: • Physical processes that can alter an optical signal during transmission or other processing such as switching • RFC4054 gives an overview • Who defines optical impairments? • ITU-T has an extensive recommendations that include terminology, definitions and measurement techniques. 73rd IETF – Minneapolis, MN, November 2008

4. ITU-T References • [G.650.1] ITU-T Recommendation G.650.1, Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable, June 2004. • [650.2] ITU-T Recommendation G.650.2, Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable, July 2007. • [G.652] ITU-T Recommendation G.652, Characteristics of a single-mode optical fibre and cable, June 2005. • [G.653] ITU-T Recommendation G.653, Characteristics of a dispersion-shifted single-mode optical fibre and cable, December 2006. • [G.654] ITU-T Recommendation G.654, Characteristics of a cut-off shifted single-mode optical fibre and cable, December 2006. • [G.655] ITU-T Recommendation G.655, Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable, March 2006. • [G.656] ITU-T Recommendation G.656, Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport, December 2006. • [G.661] ITU-T Recommendation G.661, Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems, March 2006. • [G.662] ITU-T Recommendation G.662, Generic characteristics of optical amplifier devices and subsystems, July 2005. • [G.671] ITU-T Recommendation G.671, Transmission characteristics of optical components and subsystems, January 2005. • [G.680] ITU-T Recommendation G.680, Physical transfer functions of optical network elements, July 2007. • [G.691] ITU-T Recommendation G.691, Optical interfaces for multichannel systems with optical amplifiers, November 1998. • [G.692] ITU-T Recommendation G.692, Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers, March 2006. • [G.872] ITU-T Recommendation G.872, Architecture of optical transport networks, November 2001. • [G.957] ITU-T Recommendation G.957, Optical interfaces for equipments and systems relating to the synchronous digital hierarchy, March 2006. • [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network Physical Layer Interfaces, March 2006. • [G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM applications: DWDM frequency grid, June 2002. • [G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM applications: CWDM wavelength grid, December 2003. • [G.Sup39] ITU-T Series G Supplement 39, Optical system design and engineering considerations, February 2006. 73rd IETF – Minneapolis, MN, November 2008

5. Control Plane related Applications • Impairment Aware Path Computation and Control • Our focus here • Includes path establishment and teardown • Measurement of Optical Connection Quality • Interesting potential application of control plane but we don’t address this here. 73rd IETF – Minneapolis, MN, November 2008

6. Impairment Framework Goals • Relate the application area to the GMPLS and PCE control plane (also see Giovanni) • Decompose and classify various reasonable approaches -- Very important to get folks on the same page-- • Identify, define and classify: terminology, nomenclature, parameters -- Here we reference ITU-T, but more classification for control plane purposes is useful (see Imp-Info and Giovanni) • Look for commonality and difference among approaches with respect to: (a) shared information, (b) procedures, (c) actors (entities involved) 73rd IETF – Minneapolis, MN, November 2008

7. Approaches to Impairments in WSONs ITU-T Question 12/15 Working Group List • Networks designed such that every possible path is conformant for all the signal types permitted on the network (“impairment free case”) • Networks in which a limited number of pre-calculated paths are conformant for each type of signal permitted in the network. (no knowledge of impairments in the control plane) • Networks in which impairment effects can be estimated via approximation techniques (impairment info needed) • Networks in which impairment effects must be more accurately estimated. Typically via “simulation” (impairment info needed) 73rd IETF – Minneapolis, MN, November 2008

8. Impairment Aware RWA Computation • Three conceptual functions • Routing (WSON Framework) • Finding one or more paths from source to destination • Wavelength Assignment (WSON Framework) • Selecting a wavelength/wavelengths to use along a path • Impairment Validation (IV) -- new • Determining if the impairments encountered by a specific signal on this selected path and wavelength result in unacceptable degradation in received signal quality. 73rd IETF – Minneapolis, MN, November 2008

9. Architectural Alternatives • Combined Routing, WA, and IV • Routing (R), Wavelength Assignment (WA) and Impairment Validation (IV) performed on a single entity, e.g., PCE. This doesn’t specify algorithms or procedures. Does need some type of impairment information (cases 3 & 4) • Routing + WA + IV • Splitting all or any of these functions amongst different entities. • Routing + Distributed WA/IV • Performing either WA or IV or both in a distributed fashion via a signaling protocol. 73rd IETF – Minneapolis, MN, November 2008

10. R+WA+IV • R+WA+IV • separate routing, wavelength assignment, and impairment validation • R + (WA & IV) • routing separate from a combined wavelength assignment and impairment validation process. Note that impairment validation is typically wavelength dependent hence combining WA with IV can lead to efficiencies. • (RWA)+IV • combined routing and wavelength assignment with a separate impairment validation process. Control plane implications: getting required information to computational entities and communications between entities, does not require additional signaling modifications 73rd IETF – Minneapolis, MN, November 2008

11. Routing and Distributed WA/IV Valid for Case 3: Approximate Impairment computation • RWA + Distributed IV • Does IV for only a particular wavelength • R + Distributed WA & IV • Needs to perform IV for each potential wavelength and carry this information as long as the potential wavelength is under consideration. Control plane implications: modification of signaling protocols, does not require impairment information distribution. 73rd IETF – Minneapolis, MN, November 2008

12. Next Steps/Issues • Assess interest in an Impairment Framework • Relation to other drafts? • Continue discussions with ITU-T 73rd IETF – Minneapolis, MN, November 2008